Process of improving the resistance of a mineral oil



Patented Dec. 26, 1939 I UNITED STATES PROCESS OF IMPROVING THE RESISTANCE OF A MINERAL 01L Adrianus Johannes van Peski, Amsterdam, Netherlands, assignor to Shell Development Com-. pany, San Francisco, Galifi, a corporation of Delaware No Drawing. Application March 1, 1937, Serial 4 Claims.

The invention relates to a process for manufacturing lubricating oils, insulating oils and the like, of improved oxidation-stability.

Some hydrocarbon oils, obtained synthetically, do not sufficiently comply with the severe requirements specified with regard to oxidationstability for purposes, e. g. for use in aeroplane engmes.

It is known that several synthetically produced aromatic substances have the property of rendering hydrocarbons less sensitive to oxidizing influences.

It has now been found that by adding certain substances of an aromatic character, separated from mineral'oils boiling above about 300 or fractions thereof,to high molecular weight hydrocarbon synthetic oils obtained by polymerisation or condensation of lower molecular hydrocarbons, oils are obtained of improved oxidationstability.

The stabilizing substances of aromatic character used-according to the invention, havestructures which have not yet been fully explained. They impart a higher oxidation-stability to hydrocarbon oils obtained by polymerisation or condensation of lower molecular weight hydrocar bons and to be used as lubricating oils, insulating oils and the like, than do the known anti-oxidants, whilst, moreover, they are relatively inexpensive.

The stabilizing substances added to synthetic hydrocarbon oils according to this invention are produced from the waste products obtained in the form ofextracts when refining mineral oils boiling above about'300 C. or fractions thereof, for instance lubricating oil fractions, by extract' ing same selective solvents for aromatic hydrocarbons, such as liquid S02, nitrobenzene, furfural, cresol and the like.

In the course of producing the stabilizing substances of aromatic character used according to this invention the above extracts are subjected to a refining treatment, so as to remove the olefines and the sulfur, nitrogen and oxygen compounds or to render them innocuous. It has been found to be essential that these compounds should be absent from the extracts to be added to the synthetic hydrocarbon oils. This refining treatment of the extracts may consist in a selective hydrogenation or in a treatment with sulfuric In the Netherlands March 13,

acid, aluminum chloride and similar agents.

The treatment preferably applied for refining the high-boiling mineral oil extracts comprises selective hydrogenation, carried out under conditions to remove or render innocuous undesirable components of the extracts, as it was found that the extracts refined in this manner are particularly active for improving the oxidation-stability of synthetic hydrocarbon oils. V

A suitable selective hydrogenation may consist in a treatment of the extracts withhydrogen at elevated pressure and temperatures of about 400 C. in the presence of a hydrogenation catalyst, preferably one which is immune against refining sulfur poisoning, such as a molybdenum catalyst.

The extracts from which the stabilizing substances used according to the invention are prepared are preferably derived from heavy mineral oil fractions, such as heavy lubricating oils. The refined products obtained from. extracts of relatively light mineral oil fractions, e. g. light spindle oils, are in general less suitable, since in view of their relatively high volatility they tend to reduce the flash points of the oils to which they are added to a greater extent than the heavier extracts. p

The high boiling hydrocarbon oils, produced by polymerisation or condensation of unsaturated hydrocarbons, to which my stabilizing substances are added, are here designated as synthetic hy-' drocarbon oils, and may be obtained by polymerisation of vapour phase crackedproducts of paraffin wax or paraifinous materials; or by condensation of mixtures of olefines and aromatics; or by condensation of chloroparaflins or the like with aromatics, etc.

The polymerisation or condensation may be effected either chemically, if desired in the presence of suitable catalysts, such as aluminum chloride, boron fluoride, and similar polymerisation agents, or electrically (voltolization).

The amounts of the stabilizing substances of aromatic character added to the synthetic hydrocarbon oils may vary between wide limits, depending upon the requirements. In general relatively small amounts, varying from about 1% to 10%,-

are suflicient for the purpose in view, but if. de-

sired larger amounts may be added.

The invention is further illustrated by the following examples:

Ezvample I By polymerisation of a vapor phase cracked gasoline with A1013 as catalyst a synthetic lubricating oil having a viscosity of 1.04 poises at 50 C., is produced which fails to comply with the oxidation-stability test specified by the British Air Ministry (the B. A. M. test). To this lubricating oil there is added 5% of an Edeleanu extract of a Venezuelan lubricating oil, which extract has been refined by subjecting it to a selective hydrogenation at a temperature of 400 C. and an initial hydrogen pressure of 100 atmospheres in the presence of 10% by weight of a catalyst prepared by acidifying an aqueous solution of ammonium molybdate, reducing the solution at boiling temperature with hydrogen sulfide, adding adsorbent carbon to the resulting blue-colcured colloidal solution, whereby the colloidal matter is adsorbed, and then filtering, washing and drying the carbon containing the colloidal molybdenum compound incorporated therein. The oil with the added refined extract does comply with the B. A. M. test, since the ratio of the viscosities before and after oxidation is smaller than 2.

The figures resulting from the test are given in the following table, and for comparison results ofsimilar tests in which dicetyl naphthaline is used as an anti-oxidant are also shown.

A synthetic lubricating oil having a viscosity of 1.05 poises at 50 0., obtained from a cracked distillate, boiling up to 300 (3., obtained in the cracking of a hydrocarbon material rich in paraffin wax by polymerizing same for 3 hours at 100 C. in the presence of 4% A1013, did not comply with the requirements of the B. A. M. test.

To 95 parts by weight of this oil were added 5 parts by Weight of a selectively hydrogenated lubricating oil extract, which had been prepared by subjecting an Edeleanu extract (specific gravity 01 20/4 1,0186) of a lubricating oil to three successive hydrogenation treatments during 15, 30 and 30 minutes respectively at a temperature of 400 C. and an initial hydrogen pressure of 100 atmospheres in the presence of 10% by weight of a molybdenum catalyst prepared in the manner described in Example I.

The following table gives the results of the B. A. M. tests (in duplicate) and the Ramsbottom coke number before and after oxidation of the synthetic oil with and without addition of the selectively hydrogenated lubricating oil extract.

The aboveresults show that the addition of the selectively hydrogenated lubricating oil ex- 20 tract has a pronounced improving influence on the viscosity increase through oxidation. The lubricating oil extract before hydrogenation proved to have no improving effect on the oxidation-stability of the synthetic oil, and, moreover, 25 was incompletely soluble in the synthetic oil.

I claim as my invention:

1. In the process of improving the resistance to oxidation of a synthetic lubricating hydrocarbon oil obtained by polymerizing olefines the steps 30 comprising selectively hydrogenating an aromatic, liquid SOz-soluble extract of a mineral lubricating oil containing olefinic and non-hydrocarbon impurities under conditions to eliminate at least a major portion of said impurities and 35 to produce a purified aromatic extract, and adding a small amount of the latter to the said synthetic oil.

2. In the process of improving the resistance to oxidation of a synthetic lubricating hydrocarbon oil obtained by polymerizing olefines the steps comprising selectively hydrogenating an aromatic, liquid sOz-soluble extract of a mineral. lubricating oil containing olefinic and non-hydrocarbon impurities, under conditions to eliminate said impurities and to produce a purified aromatic extract substantially free therefrom, and adding from 1 to 10% of the purified extract to the said synthetic oil.

3. In the process of improving the resistance to oxidation of a synthetic lubricating hydrocarbon oil obtained by polymerizing olefines the steps comprising selectively hydrogenating an aromatic, liquid sOz-soluble extract of a mineral lubricating oil, having a specific gravity greater than 1 and containing olefinic and non-hydrocarbon impurities, under conditions to eliminate at least a major portion of said impurities and to produce a. purified aromatic extract, and adding from 1 to 10% of the latter to the said synthetic mineral oil.

4. In the process of improving the resistance to oxidation of a mineral oil selected from the group consisting of lubricating and insulating oils, the steps comprising selectively hydrogenat- 05 ing an aromatic, liquid sOz-soluble extract of a mineral lubricating oil containing olefinic and non-hydrocarbon impurities under conditions to eliminate at least a major portion of said impurities and to produce a purified aromatic extract, and adding a small amount of the latter to the said mineral oil.

ADRIANUS JOHANNES VAN PESKI. 

